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Old 08-10-2018, 12:52 PM
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astronobob (Bob)
Casual Cosmos Capturer

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Join Date: Jun 2010
Location: Gold Coast SE QLD
Posts: 4,190
Quote:
Originally Posted by multiweb View Post
The secondary offset should be built in and the spider vanes should be kept square and centered as much as possible to avoid double diffraction spikes. Maybe the secondary has been moved and glued in a different position. The glass might also be stressed and why you're getting funny star shapes. Is it siliconed on the mounting? That's where I'd start looking.
Yes, thnx Marc, your right, the 2ndary has been originally mounted with the required 'offset' so, need to re center the spiders hub to center of tube, then adjust forward/back from main mirror to place squarely in the focus tube line-of-sight..
Cheers for your support
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